The present invention relates to an electronic module retention apparatus and more particularly to a dual action module retention apparatus for a transmit/receive module of a phased array radar antenna.
A solid state phased array radar system utilizing monolithic microwave integrated circuit (MMIC) transmit/receive modules in a phased array antenna are generally constructed such that each individual T/R module is mechanically fastened to a liquid cooled cold plate which is sized in some multiple of array elements to form an array subassembly or tray. Typical subassemblies may comprise between 32 to 48 elements and are plugged into a backplane which comprises electrical connections as well as input and output cooling manifold arrangements. Each subassembly requires expensive, leakproof, blind-mate, quick disconnect fluid coupling pairs.
To perform repairs in the field an entire tray subassembly containing many good modules must be removed, replaced with an all good subassembly, and returned to a maintenance facility for replacement of the failed module. This scheme forces a very costly spares penalty on any system inasmuch as full trays become the least replaceable unit (LRU).
One prior art approach to T/R module retention is described in U.S. Pat. No. 3,818,386, to Doyle S. Granberry, and assigned to Texas Instruments, Inc. An H shaped plate is used to secure the T/R module in place in their respective sockets of a support structure. However, the H plate is not captive to the module and comprises loose parts. Also, DC signal connection pins are provided at one end wall of the T/R module housing; they extend through a connector block which requires a hermetic seal to the end wall of the housing.
Another approach to T/R module retention in a phased array radar system is described in U.S. Pat. No. 4,998,181, to James L. Haws et al. and assigned to Texas Instruments, Inc. An all monolithic round T/R module with electrical connectors on an end wall having tiedown/eject screws attached on the side of and at the antenna end of the T/R module. This attachment device is used to affect engagement and disengagement of the electrical connector by jacking the module in and out of the main assembly. However, it does not hold the module in intimate contact with the cooling plate.
It is very desirable to be able to install or remove individual T/R modules from the tray using a single tool without the need to remove the tray from the radar antenna subsystem nor any other parts. This significantly reduces system and life cycle costs by allowing individual modules to become the least replacement unit (LRU) thereby eliminating extra tray, module, and hardware costs.
In the prior art the methodology of T/R module construction has been to form a metal enclosure with large cutouts for connectors, procure hermetic multipin and RF connectors, and weld or braze them into the housing. This methodology results in large perimeter hermetic joints with a potential risk for leakage due to voids in the weld or braze. Rework and scrap costs can be high.
It is very desirable to eliminate as many hermetic interfaces as possible. The glass compression seal around each pin is a highly reliable, well understood process that is employed to seal each pin into a connector. It follows then that if the connector pins are glassed directly into the module housing, a very large redundant hermetic joint can be eliminated. Further, if the interface features of the connectors are included in the basic housing configuration, the T/R module housing will now also serve as the connector housing. This results in lower costs, fewer components, higher reliability and a vastly reduced scrap rate.